Conventionally, headphone apparatuses have had the problem that they give an unnatural feeling as well as a feeling of fatigue to the listener because an acoustic image produced by audio signals outputted from left and right headphones are formed inside the head or near both ears which is different from the case where the audio signals are heard from speakers.
Accordingly, a variety of means have been proposed lately for the purpose of enabling the extra-head localization of the acoustic image. For example, a headphone apparatus disclosed in the document of Japanese Patent Laid-Open Publication No. HEI 3-250900 enables extra-head localization by taking reflection sounds which reach the ears through reflection on walls and the like into consideration, in addition to sounds which reach the ears directly.
However, even the aforementioned headphone apparatus still has an unnatural feeling in comparison with the case where sounds are heard from speakers or the like, and it has a problem particularly in the extra-head localization in the depthwise direction and the vertical direction. This is also apparently disadvantageous in considering the fact that we can obtain directivity of a sound even when listening to the sound from speakers in an anechoic room.
In view of the above, the present inventor has discovered that a reflection sound on the shoulder is an important factor in determining the directivity of a sound and obtaining an appropriate extra-head localization by taking into consideration how much the reflection sound is delayed on the shoulder relative to a direct sound.